class Solution:
    # @param {int[]} digits a number represented as an array of digits
    # @return {int[]} the result
    def plusOne(self, digits):
        index = len(digits)-1
        digits[index]=digits[index]+1
        while(digits[index]==10):
            digits[index] = 0;
            if(index>0):
                index = index-1
                digits[index] = digits[index] + 1
            else:
                digits.insert(0,1)
                return digits;
        return digits;


if __name__ == '__main__':
    a = Solution()
    print(a.plusOne([1,2,3]))
    print(a.plusOne([9,9,9,9,9,9]))
    print(a.plusOne([2,2,3,9]))